With the development of lighter, high revolution, high torque and more compact internal combustion engines, there has been increased need for more efficient oil cooling means. Many auto engine manufacturers have incorporated into their basic engine design the need for oil cooling means in addition to that which can be attained through traditional cooling fluid passages integrally molded into the engine block. Some manufacturers have specified the use of non-integral oil coolers which act to cool a flow of oil by means exterior to the engine block. One typical mounting means comprises mounting the oil cooling means at an oil filtering means. To satisfy the demands of the automotive industry, such cooling means must typically be compact, lightweight and capable of high heat transfer efficiency while not adversely reducing oil pressures. Thus, the continuing need to provide lighter and more efficient heat transfer devices, has occasioned the development of a multiplicity of new designs and configurations in the manufacture of heat transfer devices for use in automotive oil cooling systems.
Early externally mounted heat transfer devices generally used as oil, coolers in automotive applications typically comprised a continuous serpentine configured tube, with and without fins, mounted exterior to the engine typically in the air system in front of the radiator or within the cooling system radiator. Oil, such as transmission or engine oil and the like, is routed to flow through the tube to be cooled. A cooling medium typically was passed over the tube, for example within a coolant containing radiator or an air cooling separate unit, thus allowing energy exchange from the heated oil in the tube to the cooling medium.
With the need for compact efficiencies oil coolers were later introduced which were mounted on the engine, typically between the engine block and an externally mounted oil filter assembly, that cooled the oil going to or coming from the filter by utilizing fluid flow from the engine cooling system. These filter mounted coolers generally use multiple hollow, generally parallel spaced plate structures between which oil and cooling fluid flows in parallel planes to maximize heat transfer. Such spaced plate structures may contain fins between the hollow plate structures or are of ripple plate configuration. In such devices oil flows to the cooler from a port located at or about the filter mount and circulates between parallel plates of the cooler. Coolant from the engine cooling system circulates between and/or about the parallel plates confining the circulating oil and acts to transfer heat energy from the oil to the coolant. Many variations of the system exist, with oil being filtered first then flowing to the cooling device or the reverse and typically with coolant flowing from the cooling system of the engine, usually from the radiator or the water pump, to the cooling device.
One typical characteristic of filter mounted oil coolers is that one or both of the two fluids flow in a generally circular direction about the center of the cooler and typically the heat transfer elements, that is the fins or ripples, are typically not aligned in more than one or two directions. We have found that such configuration of the fins or ripples results in areas of decreased heat transfer efficiency to pressure drop within the heat exchanger.
A problem thus continues to exist particularly in optimizing heat transfer ratios to oil pressure drop within the heat exchanger. With the increased average operating revolutions of modern engines, coupled with the high torque and decreased response times, the need for oil cooling devices which are highly efficient and have minimum effect upon the oil pressure of the engine oiling system, have become desirable.
U.S. Pat. application Ser. No. 07/437,680 now U.S. Pat. No. 5,203,832, of which this invention is a continuation-in-part, provides for an improved energy exchange structure, wherein joined, generally parallel opposing plates are undulated in cross-section to define a plurality of opposing valleys which generally follow involute curves. The opposing valleys extend into a hollow passageway between the plates and are obliquely disposed to a circular direction of fluid flow within the passageway. Valleys of a first plate are arranged to cross valleys of a second plate such that the area between opposing valleys define crossing passages through which the fluid can flow.
One object of this invention is to provide energy exchange structures having improved heat transfer.
A further object of the invention is to provide energy exchange structures having reduced internal fluid pressure drop.
Another object of the invention is to provide an automotive oil cooler having reduced internal oil pressure drop.
A still another object of the invention is to provide a method of manufacturing an energy exchange structure having efficient heat transfer and reduced internal fluid pressure drop.
These and other objects of the invention are achieved by the invention described as follows.